A lightweight tool to filter important error lines from Android logcat output.

This tool helps developers quickly extract useful log lines such as:

• FATAL EXCEPTION
• Exception
• Error
• E level logs
• AndroidRuntime
• ANR
• Caused by

Built with Python + Streamlit.

Try the tool online:

https://logcat-error-filter.streamlit.app

Android logcat is often noisy and difficult to read.

A typical logcat output may contain:

• info logs
• debug logs
• network logs
• framework logs
• only a few lines that are actually useful for debugging

Example raw logcat:

03-11 10:01:21.123  1234  1234 I ActivityManager: Start proc 4321:com.example.app/u0a123 for activity
03-11 10:01:22.456  1234  5678 D NetworkClient: request start
03-11 10:01:23.789  1234  1234 E AndroidRuntime: FATAL EXCEPTION: main
03-11 10:01:23.790  1234  1234 E AndroidRuntime: java.lang.NullPointerException: Attempt to invoke virtual method on a null object reference
03-11 10:01:23.791  1234  1234 E AndroidRuntime:     at com.example.app.MainActivity.onCreate(MainActivity.kt:42)
03-11 10:01:24.100  1234  5678 D OkHttp: request finished

Only a few lines are truly important.

This tool extracts those lines automatically.

03-11 10:01:23.789  1234  1234 E AndroidRuntime: FATAL EXCEPTION: main
03-11 10:01:23.790  1234  1234 E AndroidRuntime: java.lang.NullPointerException: Attempt to invoke virtual method on a null object reference
03-11 10:01:23.791  1234  1234 E AndroidRuntime:     at com.example.app.MainActivity.onCreate(MainActivity.kt:42)

This makes log inspection much faster.

• Filter Android logcat output

• Extract important error-related lines

• Detect FATAL EXCEPTION

• Detect Exception and Error

• Highlight E level logs

• Show a simplified debugging view

Currently optimized for:

• Android logcat

• Android crash logs

• AndroidRuntime output

• Java / Kotlin exception lines

• ANR-related lines

Supported keywords include:

• FATAL

• Exception

• E

• AndroidRuntime

• ANR

• Caused by

The filter uses simple keyword-based matching.

Steps:

1. Split logcat into lines

2. Check each line for important error keywords

3. Keep only matching lines

4. Return a simplified error-focused output

This approach keeps the tool lightweight and fast.

Install dependencies

pip install -r requirements.txt

Run the Streamlit app

streamlit run app.py

Then open your browser:

http://localhost:8501

logcat-error-filter
│
├── app.py
├── requirements.txt
└── README.md

03-11 10:01:21.123  1234  1234 I ActivityManager: Start proc 4321:com.example.app/u0a123 for activity
03-11 10:01:22.456  1234  5678 D NetworkClient: request start
03-11 10:01:23.789  1234  1234 E AndroidRuntime: FATAL EXCEPTION: main
03-11 10:01:23.790  1234  1234 E AndroidRuntime: java.lang.NullPointerException
03-11 10:01:23.791  1234  1234 E AndroidRuntime:     at com.example.app.MainActivity.onCreate(MainActivity.kt:42)
03-11 10:01:24.100  1234  5678 D OkHttp: request finished

This project targets common developer searches such as:

• logcat error filter

• android logcat filter

• filter logcat errors

• android logcat exception filter

• androidruntime log parser

• logcat debugging tool

You may also be interested in:

• Crash Log Analyzer : https://crash-log-analyzer.streamlit.app
• Stack Trace Root Cause Finder : https://stack-trace-root-cause-finder.streamlit.app

These tools help developers debug logs more efficiently.